PRODUCTION DECLINE CURVES FOR LOW-PRESSURE GAS-RESERVOIRS UNDERGOING SIMULTANEOUS WATER PRODUCTION

A family of production decline curves for low-pressure gas reservoirs are presented for radial flow geometry with closed outer boundary and with a centrally located well. The proposed production decline curves are applicable to conventional gas reservoirs that produce gas and wat er simultaneously. The proposed decline curves exhibit unique characte ristics for a variety of reservoir and fluid properties and pressure s pecifications at the well. The performance of the proposed decline cur ves were investigated against two different numerical simulators, and they were found to be capable of predicting the production of conventi onal gas reservoirs under two-phase flow conditions with good accuracy . The decline curves presented in this paper have the potential of pro viding a practical tool by which production performance of gas reservo irs under two-phase flow conditions can be predicted for pragmatic pur poses without using sophisticated numerical models.